For a baseband frequency near 100 MHz, the application voltage to the output electrode of a high-frequency semiconductor amplifying element can be smoothed by a capacitor disposed near the output terminal of the amplifier.
On the other hand, an internally matched microwave semiconductor amplifier includes a matching circuit between the high-frequency semiconductor amplifying element and the output terminal. However, for a baseband frequency as high as 100 MHz, the applied voltage to the output electrode is difficult to smooth by a capacitor provided near the output terminal of the internally matched microwave semiconductor amplifier.